1. Field of the Invention
The present invention relates to a multiple interrupt handling method and to a corresponding apparatus, more particularly for handling a multiplicity of interrupt requests sent from a multiplicity of interrupt sources to a microprocessor, for instance in a processing unit of a telecommunication system.
2. Background of the Invention
A known method for taking account of an occurring event to be processed by means of a processor requires an interrupt request of the operation then processed to have it restarted later from the stop point as soon as possible after the event accounting.
However such a method does not fit well when there is a need for multiple interrupt handling by means of a same microprocessor as required in some processing systems, knowing that only one interrupt is processed at a time. European Patent Application 0 469 543 relates to a multiple interrupt handling circuit allowing a multiplicity of interrupt requests to be handled without exception in a processor controlled system. The circuit comprises interrupt selecting means associated with interrupt flag registering means and with latching means. It selects one interrupt request among several others simultaneously present for immediate transmission to the processor.
However, in some systems and more specifically real-time handling systems as found in telecommunication, there is a possibility of different interrupt types and/or of a large number of interrupt sources. Handling all interrupt requests would require excessive processing time and/or equipment with the known methods and apparatuses. Such a handling is even useless when the interrupt causes are either redundant or no more significant as it happens in systems, such as alarm systems in which several monitored consequences are often driven from a same action.